The LED shows power present when initially plugged in without a car on the track, and illuminates to show the brake switch is OK.The LED will extinguish when a small movement of the trigger opens the Brake contact, but will re-illuminate when the car is placed onto the track.This provides 3 useful tests with just one LED.

The Adjustment Selector Switches are sold in blocks or 4 and are a plug-in type. If the switches are accidentally damaged, simply unplug the damaged ones and plug in a new set. Instructions.